Observation of Inclusive $B$ Decays to the Charmed Baryons ${\Sigma }_c^{++}$ and ${\Sigma }_c^0$

Using data collected in the region of the $\gamma \mathrm{}\left(4S\right)\mathrm{}$ resonance with the CLEO II detector operating at the Cornell Electron Storage Ring, we report on evidence for the production of ${\Sigma }_c^{++}$ and ${\Sigma }_c^0$ baryons in $B$ decays, with ${\Sigma }_c\to {\Lambda }_c^{+}\pi$. This observation is based on $77\pm 19 {\Sigma }_c^{++}$ and $76\pm 21 {\Sigma }_c^0$ candidates from $B$ decays. We find the product branching fractions $\mathcal{B}(\overline{B}\to {\Sigma }_{c}X)\mathcal{B}({\Lambda }_c^{+}\to p{K}^{-}{\pi }^{+})$ for ${\Sigma }_c={\Sigma }_c^{++}$, ${\Sigma }_c^0$, and ${\Sigma }_c^{+}$ to be (2.1 ± 0.8 ± 0.7) × ${10}^{-4\mathrm{}}$, (2.3 ± 0.8 ± 0.7) × ${10}^{-4\mathrm{}}$, and less than 4.8 × ${10}^{-4\mathrm{}}$ at 90% confidence level, respectively. A study of the ${\Sigma }_c^{++}$ and ${\Sigma }_c^0$ momentum spectra indicates that $B$ decays to two-body final states with ${\Sigma }_c$ are suppressed.